The present invention relates to a communication system for constructing a network of household electric devices, which are conventionally used separately, and managing and controlling these electric devices.
Recently, attention has been paid to the use of communication techniques, including the Internet, in various fields. To keep pace with this movement, government restrictions have been gradually relaxed, and the construction of networks, such as CATV, local telephones and satellite communication, which involve the participation of domestic (home) users, have been developed. In addition, the following systems, for example, have been studied: a system wherein a subscriber network is constructed by using the CATV network, a system wherein conventional telephone lines are converted to wide-band ones, and an FTTH (Fiber-To-The-Home) system wherein optical fibers are extended to homes.
Various studies have been necessary on home access networks such as public networks and subscriber networks, as well as on communication terminals in homes located at terminals of subscriber networks and on home networks accommodating terminals in homes. The reason is that most of communication terminals existing in homes are telephones and facsimiles, and the other terminals are used in a stand-alone state. For example, techniques of a multimedia serial bus such as IEEE 1394, household ATM networks, etc. have been studied, and standardization of new home networks has been developed.
In the IEEE 1394 or ATM network, household personal computers, audio products, and video media transmission/reception products such as video recorders and TV sets are connected in a network. In general, there is a basic tendency that a basic plan, a set top box, a VTR, a video camera, a TV, a personal computer, etc. are to be interconnected. However, there are other types of devices which could be incorporated in a network. For example, household electric devices, such as air-conditioners, irons, electronic ovens and refrigerators, have conventionally been used as stand-alone devices. However, there is a demand for a household network constructed by interconnecting these devices by using a medium such as a power line LAN. If the household network is constructed, the turn on/off of the household electric devices can be controlled from a far place via the Internet, or the electric devices can be controlled in a centralized control manner.
In the power line LAN communication system, a power line for supplying power is used as transmission media, and power is supplied and data and messages are transmitted among the electric devices. Although there are many problems to be solved in connection with this communication system, for example, modulation of data signals, this system can achieve a network of household electric devices without varying the mode of use of conventional devices. Therefore, particular attention has been paid to this communication system.
In general, the household power line is connected via a circuit breaker to a cable from an electric power company, and it is extended to the outlets in the respective rooms. This network of the power line is called "power supply network" in this description. A general power supply network, however, is provided with only two functions: a measuring function of measuring consumed power and a circuit breaking function for stopping power supply for safety, in case power greater than a predetermined value is supplied. Such a general power supply network has no intelligent function. When high-power devices, such as a hair drier, an electronic oven, a vacuum cleaner and an air conditioner, are used at the same time and the power consumption exceeds an upper limit of household power supply, such an undesirable situation often occurs wherein the circuit breaker is switched off and, for example, a file in a personal computer, which is being edited, is lost.
As has been described above, the currently available power supply network has no intelligent function. For example, when some high-power household electric devices are used at the same time and the power consumption exceeds a predetermined value, the circuit breaker is merely activated, and all electric devices connected to the power supply network may be affected.
There arise the following problems when a network of household electric devices is constructed and power supply control is performed:
Problem 1: Information processing functional parts and communication functional parts for transmitting/receiving data within the network are expensive, and so these parts must be provided at low cost.
Problem 2: It is necessary that even a person not skilled in the network techniques can easily construct the household network. For example, such a useful function as "plug-and-play" needs to be provided.
Problem 3: When management control of household electric devices is performed by using a network, it is necessary to acquire and manage various data of the electric devices relating to the classification of electric devices and attributes (life periods, consumption power, method of use, etc.). At present, however, household electric devices have not yet been fully classified. It is highly possible that novel devices and new attributes will appear more and more, which cannot be classified according to the existing classification method. In particular, classification of new attributes is not limited to the one proposed by the standardization organization. Accordingly, classification information and attribute information is hardly managed, if it is preset in electric devices. Therefore, there is a demand for a novel management method of classification information and attribute information of electric devices, which can cope with the advent of new electric devices.